| 摘要 |
PURPOSE:To make the gain of a signal amplifying loop constant when a bar-like scintillator is used for a gamma-ray measuring instrument which measures the level of a fluid or powder by controlling the gain of the loop by using an amplifier having a variable amplification factor or multiplier while a photomultiplier is maintained at a fixed excitation voltage so as to eliminate the variation of the power consumption caused by the gain control. CONSTITUTION:Level signals generated from a plastic scintillator 5 are always amplified at a fixed amplification factor so as to make level measurement stably by subjecting the signal of a photomultiplier 6 to current-voltage conversion by means of a detecting resistor 17 and controlling the gain of a loop so that the peak of signals from a light pulser 9 can become always constant by means of an amplifier 20 having a variable amplification factor or multiplier, second comparator 13, and computing element B14 after the converted signals of the photomultiplier 6 are amplified by means of a preamplifier. |
